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E-cigarette brands and social media influencers on Instagram: a social network analysis
  1. Julia Vassey1,
  2. Tom Valente1,
  3. Joshua Barker1,
  4. Cassandra Stanton2,
  5. Dongmei Li3,
  6. Linnea Laestadius4,
  7. Tess Boley Cruz1,
  8. Jennifer B Unger1
  1. 1 Population and Public Health Sciences, University of Southern California, Los Angeles, California, USA
  2. 2 Behavioral Health and Health Policy Practice, Westat, Rockville, Maryland, USA
  3. 3 Clinical and Translational Science Institute, University of Rochester, Rochester, New York, USA
  4. 4 Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA
  1. Correspondence to Dr Julia Vassey, Population and Public Health Sciences, University of Southern California, Los Angeles, CA 90032, USA; vassey{at}usc.edu

Abstract

Background Exposure to visual posts featuring e-cigarette products on social media is associated with increased e-cigarette use among US adolescents. Instagram is the largest source of e-cigarette social media marketing, where influencers—for example, bloggers, brand ambassadors—post promotional materials. This study analysed the network of e-cigarette brands and influencers on Instagram, characterising the most central players in e-cigarette social media marketing.

Methods We tracked influencers with public profiles on Instagram who posted promotional e-cigarette content in 2020, had over 1000 followers and high user engagement rate (ratio of likes and comments to followers) of 1%–25% per post. By conducting a social network analysis, we identified the most central (highly involved in promotional activities) influencers and e-cigarette brands. The number of the influencers’ followers aged 13–17 years old and the age verification practices restricting youth access were also assessed.

Results There is a highly interconnected network of engaging e-cigarette influencers (n=55) worldwide who collaborated with over 600 e-cigarette brands in 2020. The Asian and US influencers had five to six times more teenage followers compared with the European influencers. 75% of the influencers did not restrict youth access to their promotional content on Instagram. The brands Voopotech, Innokin, Geekvape, Lost Vape, Smok and Vaporesso collaborated with the largest number of influencers (mean n=20).

Conclusions It is important to understand associations among influencers and e-cigarette use behaviours, especially youth, to inform effective public health communication and potential policies that could regulate social media marketing sponsored by e-cigarette companies.

  • social marketing
  • tobacco industry
  • public policy
  • advertising and promotion
  • electronic nicotine delivery devices

Data availability statement

Data are available upon reasonable request. Data supporting the conclusions of this manuscript will be made available by the authors, without undue reservation and in compliance with the IRB protocol, to any qualified researcher.

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi.org/10.1136/tobaccocontrol-2021-057053

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    Introduction

    E-cigarette consumption among youth around the world is a public health concern.1–3 In 2020, more than 3.5 million teenagers in the USA used e-cigarettes. During 2019–2020, the use of low-priced disposable e-cigarette devices increased approximately 1000% (from 2.4% to 26.5%) among US high school current e-cigarette users.1 In addition, more than 8 in 10 teenage e-cigarette users in the USA reported consuming flavoured e-cigarettes. E-cigarettes can harm the adolescent brain, may be associated with respiratory symptoms and may contribute to increased susceptibility to tobacco addiction.1 4–7 Exposure to visual posts featuring e-cigarette products on social media, including promotional content, has been associated with increased e-cigarette use among US adolescents,1 5 8–11 more positive e-cigarette attitudes and lower perceived danger of e-cigarette use.12

    Instagram, one of the most popular social media platforms among adolescents with approximately 1 billion users worldwide in 2021,13 is considered the second largest source of social media marketing,14 including e-cigarettes. The platform is home to content from e-cigarette stores, brands, distributors and social media influencers15 16—for example, models, bloggers, brand ambassadors with 1000 to over 1 million followers who post e-cigarette and e-liquid content on behalf of brands for monetary compensation or other non-monetary rewards (eg, free e-cigarette supply in exchange for promotion). In response to the US Food and Drug Administration (FDA) warnings about unauthorised marketing of e-cigarettes as modified risk tobacco products at schools,17 several major e-cigarette brands, including JUUL, voluntarily suspended their social media youth-oriented marketing.17 In 2019, Instagram banned all worldwide branded18 19 e-cigarette content (that features or is influenced by a business partner) from its platform. Despite FDA’s actions,20 youth-appealing content is still present on this platform. The featured products include flavoured e-liquids, flavoured disposable (eg, Puff Bars) and cartridge-based e-cigarettes, the most commonly used devices in 2020,1 as well as product packaging featuring cartoon characters and youth-appealing food. E-cigarette influencers continue to serve as a marketing tool that may be particularly effective for engaging youth. In March 2021, the FDA sent letters to e-cigarette brands (Aspire, Joyetech, Vaporesso and Voopoo) requesting information about their youth-oriented e-cigarette influencer marketing on social media21 and their actions on tracking and managing the ages of followers and viewers as well as restricting youth access to this marketing.

    A growing body of literature analyses the role of social media influencers in tobacco product marketing,22 23 finding that they are regarded as more trusted and authentic sources of content than traditional advertising.24 Focus group research among young adults suggests that tobacco-related posts made by sponsored users may be seen as more trustworthy than posts made by the brands themselves.25 Yet, influencer marketing on social media has not been studied extensively. We located no previous studies that used social network analysis26 27 to investigate brand–influencer promotion of tobacco products on social media. The social network framework shifts the focus from studying individual traits to analysing interactions, relationships and communications.28 Social network analysis captures distribution of a specific content (eg, promotional posts on social media) and identifies users who are responsible for distribution of this content. For example, Himelboim and Golan28 analysed the role of social media influencers in diffusion of social media beer advertising on Twitter. The study identified primary influencers (highly retweeted users), bridges (connector hubs who spread information from followers of one influencer to another) and isolates (low-influence users with limited individual contributions to content distribution, but with substantial cumulative influence).

    A social network is formed when connections (‘ties’) are created among social actors (‘nodes’), such as individuals (eg, social media influencers) and organisations (eg, e-cigarette brands). Therefore, one way to capture brand–influencer relationships is to examine the number of ties or connections between brands and influencers. These connections are measured by degree centrality,29 30 a commonly used measure in social network analysis, which is the number of ties a node has to other nodes. Nodes that have more ties are considered more central, that is, important and influential since they can play a key role in content distribution. For example, if an e-cigarette brand collaborates with multiple influencers, the content they promote on social media may potentially reach a larger network of the influencers’ followers. Similarly, influencers who collaborate with multiple e-cigarette brands might expose their social media followers, including youth, to a wider variety of tobacco-related content. Considering potential exposure to harmful content, social network analysis merits consideration in tobacco control regulation of industry marketing tactics.

    This study is the first to analyse the network of e-cigarette brand–influencers on Instagram, providing a global view of potential collaboration among US and international influencers. The study aimed to: (1) identify the most engaging e-cigarette influencers on Instagram in 2020; and (2) conduct a social network analysis to characterise connections between the most central influencers and e-cigarette brands these influencers promoted on Instagram.

    Materials and methods

    Data collection

    In October-–December 2020, we used a commercial social media listening platform Meltwater31 to track Instagram influencers with public profiles and over 1000 followers who posted promotional content that included the most frequently used e-cigarette hashtag and keyword ‘vape’. Using this search term, we identified 260 influencers who posted about e-cigarettes in English in 2020 (posts were collected over the whole year both prospectively and retrospectively).

    Identifying the most engaging e-cigarette influencers

    Of the 260 influencers’ profiles, we selected 55 influencers who met all of the following criteria considered metrics of good performance and high engagement: (1) having more than 1000 followers32; (2) having at least 2:1 ratio33 of the number of followers to the number of users who an influencer follows; (3) having high engagement rate (1%–25% per post) based on the engagement rate benchmarks on Instagram frequently cited by social media analysts34 (ie, 6-month average engagement rate per post, which is a sum of ‘likes’ and comments divided by the number of followers); (4) posting e-cigarette promotional content at least once a month over 12 months in 2020.

    Characterising e-cigarette influencers and their promotional content

    We collected the following influencer profile metrics (table 1):

    View this table:
    Table 1

    Metrics collected about social media influencers (n=55) who posted promotional e-cigarette content on Instagram in 2020

    The influencers’ Instagram profile descriptions and captions to their e-cigarette 2020 promotional posts (N=9280) were then examined by four independent coders (one of the coauthors of this study and three undergraduate student assistants). The assistants were trained to identify any indication of the influencers’ association with an e-cigarette brand (eg, a mention of an e-cigarette brand in a post’s caption, figure 1A and C). Brand names were documented.

    Figure 1
    Figure 1

    Evidence of collaboration between influencers and e-cigarette brands. (A,B) E-cigarette brands mentioned in captions to the influencers’ Instagram posts; (B,C) example of a violation* of the Federal Trade Commission (FTC) guideline for sponsorship disclosures. *When a post is viewed on a mobile device, the brand name gets truncated requiring a user to click ‘more’ (B) to see a brand name (C). Publicly available photographs and captions were sourced from the public Instagram account of an influencer Drewdirps on December 2020 (https://www.instagram.com/drewdirps/).

    The coders also evaluated the posts for the presence (‘yes’/’no’) of the fully compliant Federal Trade Commission (FTC)-required sponsorship disclosure,35 36 that is, (a) a description of collaboration with an e-cigarette brand that discloses either monetary compensation or non-monetary rewards (eg, ‘a product provided by X brand in exchange for Y service’); and (b) the placement of this disclosure at the top of the Instagram caption (which is relevant for mobile devices when longer descriptions get truncated and users need to click ‘more’ to view the complete caption text,35 figure 1B,C). The coders also reviewed non-e-cigarette promotional posts (N=1992) to document other topics featured in the influencers’ 2020 Instagram posts.

    Social network analysis method

    We conducted a social network analysis26 27 to describe connections between e-cigarette brands and the most engaging e-cigarette influencers (n=55) by identifying the most central brands and influencers in the network. The primary metric we use is degree centrality,37 which represents the number of e-cigarette brands an influencer partners with and the number of influencers an e-cigarette brand partners with. We used a two-mode network,38 39 which characterises ties existing between two distinct types of nodes (eg, e-cigarette brands and e-cigarette influencers), but not ties within brands or within influencers. We treated e-cigarette brands as a primary (tie-creating) mode of nodes and e-cigarette influencers as a secondary mode of nodes. We justified this classification based on the assumption that e-cigarette brands could be considered more responsible for creating ties with influencers by inviting them to collaborate on product promotion. We also classified e-cigarette brands as a primary mode since we identified them in this manuscript: this information may be valuable for the FDA that periodically issues warning letters to specific tobacco brands in an attempt to regulate their promotional activity. We de-identified influencers (the secondary mode) by masking their Instagram usernames, in compliance with the Institutional Review Board protocol.

    We colour-coded geographical region USA as red, Asia as green, Europe as blue and ‘Other’ as pink represented by one influencer from South Africa and one from Brazil. We defined the North America region as the USA, because only one influencer from Canada met the inclusion criteria; the rest were from the USA.

    Descriptive statistics

    For descriptive analysis, we divided e-cigarette brands into three categories based on their degree centrality, that is, the number of influencers with whom they collaborated. The categories included e-cigarette brands that were connected to: (1) more than 10 influencers (the maximum was one brand that worked with 27 influencers); (2) 5–10 influencers; and (3) 1–4 influencers. For each of these three categories, we provided the average number of the US, Asian and European influencers’ followers, including the number of teenage (13–17 years old) followers, and the average engagement rate (table 1) to assess popularity of the influencers’ e-cigarette content in their network.

    Similarly, we divided the influencers into three categories based on their degree centrality (high, mid-range and low degree centrality). Among these three categories, we compared self-identification of the influencers in their profile descriptions (eg, ‘influencer’, ‘blogger’, ‘public figure’), compliance of their posts with the FTC requirements for sponsorship disclosures,35 36 and the diversity of their promotional content (if they posted exclusively about e-cigarettes or about other topics as well). Coders also documented the number of brands’ followers, including teenage followers (13–17 years old), and whether the brands and influencers had age-gating notifications (eg, this content is for 18+ or 21+ audience) on their Instagram profiles. In addition, our 20-year-old and 17-year-old coders attempted to follow these e-cigarette brands and influencers on Instagram for the purpose of this study.

    Cohen’s kappa for the initial inter-rater reliability (IRR) ranged from 0.87 to 0.95. Differences in coding were discussed and reconciled by the coders until the final IRR for all categories reached >0.95.

    Inferential statistics

    The one-way analysis of variance test followed by the Tukey Honest Significant Differences test for pairwise comparison were conducted to estimate mean differences in the number of followers and engagement rates among the three groups based on the influencers’ geolocation (USA vs Asia vs Europe). The social network and statistical analysis were conducted in R.

    Results

    Social network of e-cigarette brands and influencers

    The 55 most engaging e-cigarette influencers collaborated with 640 e-cigarette brands that the influencers disclosed in their Instagram captions. In the full network of 640 brands, 5 (9%) of the influencers had the highest degree centrality, collaborating with 60–90 e-cigarette brands, 34 (61%) had mid-range degree centrality, collaborating with 11–50 brands, and 16 (30%) had low degree centrality, collaborating with 10 or fewer brands.

    To simplify the social network visualisation, we restricted the social network analysis to the e-cigarette brands that collaborated with five or more influencers (n=45 brands, n=52 influencers; figure 2).

    Figure 2
    Figure 2

    A two-mode network of the most central e-cigarette brands (primary mode, n=45) that from January to December 2020 collaborated with five or more Instagram influencers (secondary mode, n=52).

    Figure 2 shows a highly interconnected network comprised of e-cigarette brands that promoted their e-cigarette products in 2020 on Instagram via influencers from all over the world, primarily from the USA, Indonesia, Germany, France, Malaysia and Italy. We identified 18 influencers from the USA (red), 12 from Asia (green), 20 from Europe (blue) and 2 influencers from South Africa and Brazil (pink). The full distribution of the influencers’ country-wide geolocation in our dataset is presented in online supplemental figure 1.

    The influencers with the highest degree centrality (larger circles located near the centre, figure 2) were primarily from Asia followed by the USA. The influencers with lower degree centrality (smaller circles located further away from the centre) represented all three regions, but the majority were from Europe and the USA.

    E-cigarette brands with the highest degree centrality collaborated with predominantly the same influencers

    Twelve e-cigarette brands (table 2)—big China-based manufacturers and worldwide distributors of e-cigarette products—had the highest degree centrality, collaborating with the largest number of influencers (17–27). Proximity of the squares representing these e-cigarette brands (figure 2) indicates that they mostly collaborated with the same influencers (sharing more than 70% of them). These e-cigarette manufacturers also collaborated with Asian influencers who had the highest degree centrality (ie, they collaborated with 10–18 brands in the restricted network of 45 brands), and with European and US influencers who had lower degree centrality (they collaborated with 5–10 brands in the restricted network of 45 brands).

    View this table:
    Table 2

    Characteristics of e-cigarette brands (N=640) by the number of influencers they collaborated with, the influencers’ user engagement and the number of the influencers’ followers on Instagram in 2020

    E-cigarette brands with mid-range degree centrality collaborated with the European influencers who were distinct from those working with the most central brands

    Thirty-three e-cigarette brands (table 2)—manufacturers, distributors and retailers from China, the USA, and the UK—had mid-range degree centrality (collaborating with 6–10 influencers) or low degree centrality (collaborating with five influencers). Brands with mid-range degree centrality hired predominantly the same US and Asian influencers as did the most central e-cigarette brands but had distinct European influencers who did not collaborate with the most central brands

    E-cigarette brands and influencers with the low degree centrality appeared to be relatively disconnected

    Peripheral brands with low degree centrality, located away from the centre (figure 2), were more ‘contained’ in their niche market rarely sharing influencers. These e-cigarette brands partnered with US and European influencers with relatively small degree centrality (collaborating with 1–5 e-cigarette brands in the restricted network of 45 brands). These brands also collaborated slightly less frequently with Asian influencers compared with the more central brands.

    Descriptive and inferential statistics

    Influencers’ followers and engagement

    The number of influencers with whom the brands collaborated appeared to be very right skewed. Twelve brands collaborated with more than 10 and up to 27 influencers, 33 brands collaborated with 5–10 influencers, and most of the brands (n=595 brands) collaborated with 1–4 (table 2).

    Across all categories (table 2), on average, Asian and US influencers had about five times more followers overall and about six times more under 18-year-old followers compared with European influencers (p<0.05). The e-cigarette content posted by Asian influencers was about three times more engaging than e-cigarette content posted by US and European influencers (p<0.05).

    Influencers’ profiles

    All the influencers included in our analysis typically described themselves in their Instagram profiles as ‘public figure’, ‘brand ambassador’, ‘promoter’, ‘video creator’, ‘artist’, ‘photographer’, ‘blogger’, ‘model’ or ‘fitness lover’. The word ‘influencer’ was rarely used (only by two influencers). Gender representation was almost equally split between male and female: 50% of them (27) were female. Sixty per cent of the influencers mentioned e-cigarette brands they collaborated with on their Instagram profiles, included descriptions such as ‘promotion’, ‘sponsored’, ‘endorsements’, ‘collaboration’, or provided their contact phone or email for business inquiries. Influencers with the highest degree centrality had on average 103 000 followers (SD=74 100, range=2100–221 400). This was three times the number of followers of the influencers with mid-range and lower degree centrality (p<0.05). On average, 4% of the most central influencers’ followers were 13–17 years old, which was three times the number of teenage followers (1%) of the less central influencers.

    Sponsorship disclosures

    Only 5% of the influencers’ posts had sponsorship disclosures19 fully compliant with the FTC requirements, that is, positioned at the very top of a caption or had a description of the type of collaboration, for example, ‘a product provided by X brand in exchange for Y service’.

    Variety of content posted by e-cigarette influencers

    Twenty percent of the influencers (11 out of 55) posted exclusively e-cigarette-related promotional content, while the majority—80% (44)—had other promotional topics featured in their posts besides e-cigarettes, including cannabis (CBD) products, fashion, nicotine chewing gums or pouches, and beauty products (figure 3). Still, most of the posts (N=9280) of almost all the influencers were-e-cigarette related (online supplemental figure 2).

    Figure 3
    Figure 3

    Proportion of the influencers (n=55) who posted exclusively about e-cigarettes (n=11 or 20%) compared with the influencers (n=44 or 80%) who posted about e-cigarettes and other topics on Instagram in 2020.

    We found that more than 60% of the e-cigarette brands (n=45) had no age-gating restrictions for followers, although about 40% stated that their posts were only for age-appropriate (18+ or 21+) users. Similarly, 41 out of 55 (75%) of the influencers had no age-restricting notifications. Our 20-year-old and 17-year-old coders were able to follow over 60% of the brands and all the influencers.

    Discussion

    Despite FDA’s actions against any e-cigarette ads targeting youth6 20 21 40 and the Instagram ban on sponsored e-cigarette content,18 19 in 2020 influencers were still collaborating with e-cigarette companies and promoting specific brand-related content on the youth-popular social media site, Instagram. This cross-sectional study analysed Instagram user profiles of 55 engaging influencers with at least 1000 followers and characterised their connections with over 600 e-cigarette brands to promote e-cigarette-related content.

    The social network analysis in this study provided a methodology that may be relevant for tobacco control policy regulators such as the FDA to identify the connections among e-cigarette companies that use brand ambassadors and influencers to post youth-appealing content. By applying the social network method, we discovered a highly dense and intertwined brand–influencer network. E-cigarette brands often hire the same influencers from all over the world, primarily from the USA, Indonesia, Germany, France and Malaysia. International borders on social media are absent. E-cigarette international content could reach US audiences, since influencers from different countries comment on and ‘like’ each other’s Instagram posts, potentially exposing their followers to broader e-cigarette promotional materials.

    The social network analysis also allowed us to distinguish the network of influencers used by the most central versus less central e-cigarette brands. The most central brands are large China-based manufacturers and worldwide distributors of a variety of e-cigarette products, including flavoured disposable devices. In 2020, they collaborated with up to 27 US and international influencers (especially Indonesian and Malaysian) with a large number of followers. Less central brands appeared to be smaller manufacturers, distributors and retailers that concentrated more on their respective local markets (US, Asian or European).

    The study described the potential reach of the influencers based on their engagement, followers and geolocation. Asian influencers had the highest engagement rate compared with US and European influencers. Both US and Asian influencers had a follower base averaging 90 000, with about 5% of those under 18 years. European influencers had smaller number of followers and smaller under 18-year-old audiences of about 1%. It is an empirical question for further study to explain the association between the e-cigarette influencers’ geolocation, their engagement rate and the number of their followers. It is possible that the absence of policy restrictions on e-cigarette use in Indonesia and Malaysia allows social media e-cigarette influencers in these countries to actively engage with their audiences and have higher reach among youth. In contrast, the smaller number of teenage followers of European influencers could be attributed to more frequent use of Instagram’s 18+ age restriction tool, compared with US and Asian influencers, or European Union (EU) policies (eg, EU Tobacco Products Directive and the Tobacco and Related Products Regulations).41 42

    Our study also showed that regardless of the region (USA, Asia or Europe), the influencers’ e-cigarette promotional posts were rarely fully compliant with the FTC-required sponsorship disclosures.35 36 Also, very few e-cigarette brands and influencers used the age-gating feature on Instagram (restricting youth access), despite stating on their Instagram profiles that their content is for the 18+ or 21+ audience. Moreover, Instagram seems not to diligently adhere to its own age-gating policy, since teenage users can easily provide a fake age over 21 years. Prior research suggests that youth regularly enter fake ages to obtain access to platforms and content.43 44 Because of this loophole, the number of under 18-year-old followers reported in this study may be underestimated.

    Finally, influencers often collaborate with multiple industries (eg, fashion, beauty products, healthy lifestyle) in addition to e-cigarette brands. These influencers could potentially expose their non-e-cigarette-focused audience (including non-users of e-cigarettes) to e-cigarette content. Thus, these influencers could be considered an even higher risk for youth compared with those who post exclusively about e-cigarettes. That is especially problematic because most e-cigarette brands claim that their advertising and promotional content is meant to target current cigarette smokers to help them switch to e-cigarettes,45 46 rather than people who do not use nicotine at all.

    The results from this study should provide guidance for future research. A social network analysis of influencers’ interactions and users’ reactions to their promotional e-cigarette posts on social media would be an important future direction to expand this work and understand diffusion of information about e-cigarette marketing. Another important direction is to characterise variations in influencer marketing strategies and types of promoted e-cigarette and other tobacco products among different racial/ethnic groups to address disparities in tobacco product exposure on social media.

    Limitations

    Since accessing the Instagram Application Programming Interface directly became impossible for non-commercial parties after 2016, we used a commercial social media listening platform Meltwater for data collection. Although Meltwater, based on their agreement with Instagram, provides access to a rich dataset of over 10 million influencers with public profiles who post on a variety of topics, the sample from which we selected e-cigarette influencers might have been not truly random.

    It is not possible to say with absolute certainty that all posts made by influencers were truly sponsored, since some influencers may also upload content that they were not incentivised to post about. This may overstate the number of sponsored posts, as well as complicate enforcement efforts.47

    We only conducted a descriptive analysis and looked at the most frequently used measure in social network analysis, degree centrality. We did not assess the effect of exposure to promotional content on followers or product users.

    Finally, we only reviewed the posts’ accounts and captions written in English. Translating and analysing captions to e-cigarette promotional posts in other languages could be a direction for future research.

    Conclusions

    Instagram is home to many social influencers with widespread audiences, including youth, high levels of engagement and a highly interconnected, dense social network. The influencers often post promotional images and videos of e-cigarette products without disclosing their incentive arrangements with e-cigarette brands. This type of marketing deserves closer research and policy attention to reduce tobacco product influence, especially among youth. Even if policies were to enforce disclosure requirements more strongly, youth and non-users of e-cigarettes could still be exposed to non-compliant content posted by influencers from other countries. Similarly, when e-cigarette influencers from different countries react to (comment on or ‘like’) each other’s posts, they potentially expose their respective audiences to each other’s promotional content. Social media influencer marketing is no longer dominated by mega-influencers with millions of followers, but is powered by an interconnected global network of micro-influencers48 49 (with 1000–100 000 followers) who collaborate with multiple industries and multiple brands, including tobacco. Large e-cigarette brands also have a global network of smaller distributors and retailers whose products are promoted by influencers. While it may be difficult for public health officials to regulate this interconnected global network, improved monitoring of how social media sites implement and enforce their own restrictions on tobacco-related content may help overcome this hurdle.

    What this paper adds

    • Exposure to influencer marketing and other promotional strategies related to e-cigarette content on social media has been associated with increased risk of e-cigarette use among adolescents and young adults.

    • Despite the US Federal Food and Drug Administration (FDA) actions against any e-cigarette ads targeting teenagers and the Instagram ban on e-cigarette-branded content, youth-appealing promotional posts are still present on this platform.

    • Influencer marketing on social media has not been studied extensively. This study is the first to analyse the network of e-cigarette brand–influencers on Instagram, providing a global view of potential collaboration among US and international influencers.

    • We discovered a highly interconnected network of engaging e-cigarette influencers (n=55) worldwide who collaborated with over 600 e-cigarette brands in 2020. Most of the influencers we reviewed did not restrict youth access to their promotional content on Instagram.

    • The US and Asian influencers had a follower base averaging 90 000, with about 5% of those under 18 years, which is sizeable considering the large number of followers.

    Data availability statement

    Data are available upon reasonable request. Data supporting the conclusions of this manuscript will be made available by the authors, without undue reservation and in compliance with the IRB protocol, to any qualified researcher.

    Ethics statements

    Patient consent for publication

    Ethics approval

    This research was approved by the Institutional Review Board (IRB) of the University of Southern California (USC): UP-21-00352.

    Acknowledgments

    The authors acknowledge the contribution of the undergraduate students Sofia Santoro, Jacqueline Usibelli, Ashley Smith, Ali Zafar-Khan and Ana Alexandra Natividad, Department of Population and Public Health Sciences, University of Southern California (USC), for their assistance with coding of the influencers’ posts and documenting e-cigarette brand names mentioned in the posts. The authors acknowledge that figure 1 contains a publicly available Instagram image of an influencer with a public Instagram account.

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    Supplementary materials

    Footnotes

    • Twitter @LinneaLaestad

    • Contributors JV conceived the paper and wrote the first draft of the manuscript. All coauthors provided feedback on the first draft and substantial writing to the final version of the paper. All coauthors approved the final version. JV acts as a guarantor.

    • Funding Research reported in this publication was supported by the National Cancer Institute and the Food and Drug Administration Centre for Tobacco Products (CTP) (grant # U54 CA180905, U54CA228110), the National Institute of Health (grant # 1R01CA260459-01), the National Centre for Advancing Translational Sciences (grant # UL1TR002001), and the Centre for Coordination of Analytics, Science, Enhancement and Logistics (CASEL) in Tobacco Regulatory Science (grant # U54DA046060-01).

    • Disclaimer The funders had no role in study design; collection, analysis, and interpretation of data; writing the report; and the decision to submit the report for publication. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funders.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.